Magneto-resistive (MR) thin film sensors used for low field sensing applications usually take the form of long stripes with a width of several microns and a length of tens of microns, up to about 100 microns [1]-[3]. With such a large aspect ratio, the shape anisotropy of the long stripe helps to maintain the magnetic domain structure within the sensing layer of the device (which has a thickness of <10 nm in most cases). Prior work [4] also shows that reducing the gap between adjacent stripe patterns can help alleviate the “stiffness” of the sensor caused by the shape anisotropy of the long stripe. Thus, the sensitivity of the multi-stripe sensor array can be improved, as we will discuss below.
A routine search of the prior art was performed with the following additional references of interest being found:
U.S. Pat. No. 7,283,336 (Gill) shows a single-domain free layer having a bias field at side edges of the read sensor. U.S. Pat. No. 7,203,039 (Wang et al—Headway) discloses an additional layer of soft magnetic material abutting hard biasing layers to prevent flux leakage. U.S. Pat. No. 7,016,166 (Hou et al) shows biasing structures abutting each side of the single domain MR structure. U.S. Pat. No. 6,873,499 (Lee et al) shows flux guides abutting the read sensor.